Climate change is the single greatest health concern confronting humanity, and health experts all across the world are already reacting to the consequences of this emerging calamity. The Intergovernmental Panel on Climate Change (IPCC) has decided that the world must restrict temperature rise to 1.5°C to avoid catastrophic health effects and millions of climate change-related fatalities. Past emissions have already made a certain level of global warming and other climate impacts unavoidable. Even 1.5°C of global warming is not regarded as safe; every tenth of a degree of warming will have a significant impact on people's lives and health. While no one is immune to these dangers, those whose health is most affected by the climate catastrophe are those who contribute the least to its causes and are least able to protect themselves and their families - individuals in low-income and disadvantaged countries and communities. Climate change is already having an impact on health in a variety of ways, including increased death and illness from increasingly common extreme weather events like heatwaves, storms, and floods, food system disruptions, increases in zoonoses and food-, water-, and vector-borne diseases, and mental health issues. Furthermore, many of the social determinants of human health, such as livelihoods, equality, and access to health care, as well as social support structures, are being harmed by climate change.